1. Field of the Invention
The invention relates to a novel process for preparing an aldehyde compound via hydroformylation of an ethylenically unsaturated organic compound. The process is catalyzed using a unique bidentate phosphite ligand along with a Group VIII metal, such as rhodium.
2. Background Information
Hydroformylation is a known process by which an ethylenically unsaturated organic compound (such as an olefinic compound and organic compounds carrying functional groups) is converted to an aldehyde containing one carbon more than the starting ethylenically unsaturated organic compound. Specifically, the ethylenically unsaturated organic compound is reacted with hydrogen and carbon monoxide in the presence of a hydroformylation catalyst. The economics of this process require a coordination of maximizing conversion and selectivity at minimum operation cost and low catalyst cost.
There still remains a need for an improved hydroformylation process that is highly efficient and cost-effective, and which maximizes selectivity of the desired product. U.S. Pat. No. 5,235,113 (and related European Patent Application 518,241 and U.S. Pat. Nos. 5,391,801) describe a hydroformylation process using as a catalyst rhodium and a bidentate phosphite ligand. The hydroformylation of 1-octene, toluene, mixed octene, 1-butene, and 1-tetradene is described. The entire contents of EP-A-518,241 and of U.S. Pat. Nos. 5,391,801 and 5,235,113 are incorporated herein by reference.
The ligands in U.S. Pat. No. 5,235,113 are described according to the following general formula: EQU A--[O--P(OR) (OR)].sub.2,
wherein A represents a divalent organic group and R represents an organic group. Unfortunately, the practice of this process still exhibits the unresolved problem that a significant amount of the original olefinic compound is hydrogenated to form an unwanted by-product. This is a serious inefficiency in the process described by U.S. Pat. No. 5,235,113.